This is a collaborative project between biomedical researchers at the Michigan State University schools of medicine, and faculty and staff at the Ministry of Health, and Faculty of Medicine, University of Khartoum, Democratic Republic of Sudan. It focuses on fundamental aspects of three major tropical disease entities which impose major constraints on the health, productivity, progress and potential of the Sudanese people. In the coming year (September 1980-August 1981) we propose to build on the foundations laid by our current efforts in the establishment, renovation and equipping of laboratory and field bases in Sudan, the development of cooperative agreements between scientific participants from all the institutions involved, and the delineation of reasonable programs of investigation, suited to the priorities, environment and immediate opportunities in Sudan. In schistosomiasis, we intend to consolidate our preliminary studies on the spectrum of therapeutic regimens used in Sudan and their place in medical care and preventive medical strategies, by developing a detailed clinical/pharmacological investigative protocol: this will be applied both to the agents presently routinely administered and to others to which we hope to have access as their suitability for trial purposes is evaluated. In malaria, we shall begin to collect and characterize Plasmodium falciparum strains, and measure the effects of immune factors on the outcome of in vitro assays of drug sensitivity. Results will be evaluated in relation to other strains from Africa, Asia and Latin America. Onchocerciasis transmission in Sudan will be studied through field collections of data on vector type, availability and distribution and correlated with epidemiological data on infection rates and intensity in humans. Preliminary studies will be undertaken to develop immunologic reagents for the detection and purification of antigens of O. volvulus for immunopathological work in the future.